Preparation of beta-alanine



Patented N... 16, 1943 Philip M. Kit-k, Stamford, Conn, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application June 25, 1942,

. Serial No. 448,486

8 Claims. (Cl. 260-534) This invention relates to the preparation of beta-aminopropionic acid (beta-alanine) and more particularly, to the preparation of betaaminopropionic acid in one step from bis-(cyanoethyl) amine and ammonium hydroxide.

Accordingto the present invention we have found that bis-(cyanoethyl) amine and ammonium hydroxide, when heated together in apressure vessel at temperatures ranging from about 180 C. to about 225 C. for from about one to about twenty-four hours, react to produce betaaminopropionic acid. If desired, a small amount of a corrosion and oxidation inhibitor such as,

for example,- diphenyl-amine may be added to the reaction mixture.

Beta-aminopropionic acid has recently become an important intermediate in the preparationor pantothenic acid and accordingly, a commercially practicable methodfoi preparing this intermediate is indicated. .The process of the present-invention provides such a'method.

It is an advantage of the present invention that the only reactants essential for the operation of the process are bis-(cyanoethyl) amine and am-, monium hydroxide. The latter is, of course,

. readily available and cheap; the former is readily available and not disproportionately expensive since it may be obtained as a by-product formed when acrylonitrile is treated with ammonia.

It is another advantage of the present invention that the'reaction involved is simple, easily controlled, and takes place in a single step. Thus.

beta-aminopropionic acid may be-produced directly'irom bis-(cyanoethyl) amine without requiring the isolation of any intermediate product. g

It is a iurther advantage or the invention that the beta-aminopropionic acidis obtained in good yield in a form which permits easy separation from the reaction mixture.

The invention will be described in greater de-' tail in conjunction with the iollowingspecific examples. It should be understood that these examples are ,merely specific embodiments-of the invention and it is not. intended to limit the.

scope of the invention to the specific details therein set forth. Parts are by weightunless otherwise stated. Example 1 200 parts 1.53 molsl a. bis- (cyanoethyl) amine, 000 parts of 28% ammonium hydroxide.

1080 parts or water and 2 parts or diphenylamine were'heated to 200 C. for tour hours in an autoclave. The solution was filtered, treated with Yield: 24%

syrup was then diluted with 500 mls. of methanol. whereupon 59 parts of beta-aminopropionic acid suitable for the production or pantothenic acid without further purification crystallized out.

Example 2 After recovery of the beta-aminopropionic acid as described in Example 1, the filtrate was evaporated to reclaim the methanol. The resulting syrupy residue was heated with an additional amount of ammonium hydroxide at 200 C. for four hours and the solution treated as described in Example 1. A simflar further yield of beta- I aminopropionic acid crystals was obtained.

Apparently an equilibrium is reached in the reaction between his (cyanoethyl) amine and ammonium hydroxide which may account for the fact that the residue from one operation may be used as the reactantin another with no appreciable decrease in the yield of beta-aminopropionic acid obtained. When over-all yields are considered, this feature or my Process is extremely important since yields approaching the theoretical may be obtained by re-working. the residues.

Further evidence tor the existence of an equi librium mixture was obtained from a series of further reactions-wherein concentrations or the reactants, time of heating and temperature were varied within wide limits. The strength otthe ammonium hydroxide was varied from 2% to 28% with similar variations in the proportion of bis-(cyanoethyl) amine based on-the proportion oi. ammonia; the'time of heating, from one to twenty-four hours; and the temperature, from 150 to 250 C. In all cases beta aminopropionic acid was obtained but only drastic changes inthe concentration of reactants gave more than a 35% yield. For example, very low concentrations or bis-(cyanoethyl) amine produced beta-amino- P p ni i acid in yields of the order or 50%-60% but theincreased cost or removing the larger volumes or solventpresent would probably, neutralize the economical advantages resulting 1mm the increased yields. I

The beta aminopropionie acid produced by my process may,.ii' desired. be converted toan acid" salt such as the'hydrochloride or to a salt at a metalsuchasanalkalioralkalineearthmetal,

and isolatedin-this form. I prefenz-however, to

- isolate the'beta-aniinopropionie acid directly from the concentrated my reaction product by diluting it withabsollitc methanol. Whenso isodecolorizing carbon at '10 0., "immune. and

the filtrate evaporated to a thick m lated. the acid is minor. x

form and "then, it desired, be convertedto the salts when they are required as intermediates in processes for producing pantothenic acid.

Methanol appears to be peculiarly suited for the above isolation or crystallization step. At-

tempts to dilute with various other aliphatic alcohcls such as ethanol or propancl have been unsatisfactory.

In the reaction between bis-(cyanoethyl) amine and ammonium hydroxide under the conditions described above, it may be desirable in some instances to add other substances to the reaction mixture. For example, dehydration catalysts, ammonium salts of weak acids such as ammonium carbonate, inhibitors, anti-oxidants, and other suitable reagents for slightly altering the course or speed of the reaction may be added.

I claim:

1. The process of producing beta-aminopropionic acid which comprises reacting bis-(cyanoethyl) amine with aqueous ammonia at a temperature of from about 180 C. to about 225 C.

2. The process of producing beta-aminopropi- 5. The process of producing beta-aminopropionic acid which comprises reacting bis-(cyanoethyl) amine with aqueous ammonia at a temperature of about 200 C. for about four hours, concentrating the reaction mixture to a syrup, and diluting the syrup with methanol to cause precipitation of beta-aminopropionic acid.

6. The process according to claim 1 in which 1 the residue produced by reacting bis-(cyanoethy l) onic acid which comprises heating bis-(cyano:

ethyl) amine and aqueous ammonia at a temperature of about 200 C. for from about one to about twenty-four hours.

3. The process of producing beta-aminopropu onic acid which comprises heating bis-(cyanoethyl) amine and aqueous ammonia at a temperature of about 200" C. for about four hours.

4. The process of producing beta-aminopropionic acid which comprises reacting bis-(cyanoethyl) amine with aqueous ammonia at a tem-' perature of from about 180 C. to about 225 C. for from about one to about twenty-four hours,

. concentrating the reaction mixture to a syrup,

and diluting the syrup with methanol to cause precipitation of beta-aminopropionic acid.

amine with aqueous ammonia is reacted with a fresh .quantity or" aqueous ammonia at an elevated temperature to produce a further quantity of beta-aminopropionic acid. I

7. The process of producing beta-aminopropionic acidwhich comprises reacting bis-(cyanoethyl) amine with aqueous ammonia at a temperature of from about 180 C. to about 225 C. for from about one to about twenty-four hours, concentrating the reaction mixture to a syrup, diluting the syrup with methanol, collecting the precipitated beta-aminop'ropionic acid, concen trating the residue, and reacting said residue with aqueous ammonia at a temperature of from about 180 C. to about 225 C. for from about one to about twenty-four hours to produce a further quantity of beta-aminopropionic acid.

8. The process of producing beta-aminopropionic acid which comprises heating at a temperature of about 200 C. a mixture of bis-(cyanoethyl) amine and aqueous ammonia for about four hours, concentrating the reaction mixture to a syrup, diluting the syrup with methanol, 

